1. Field of the Invention
The present invention generally relates to a logging into place tool. More particularly, the present invention relates to a logging into place tool having a gamma-ray tool and an electromagnetic telemetry tool attached to a drill stem test string.
2. Background of the Related Art
A drill-stem test (DST) system is commonly used in connection with hydrocarbon exploration and exploitation. The primary purpose of the DST is to obtain a maximum stabilized reservoir pressure, a stabilized flow rate, and representative samples formation fluids and gasses. The hydrocarbon reservoir""s potential is evaluated utilizing various reservoir engineering calculations and the collected data/information.
Drill stem test systems commonly have a multi-section housing which contains or supports a number of test-related devices, which collectively may be referred to as the drill stem test tool or DST tool. The housing sections are formed with internal conduits which, when the housing sections are assembled, co-operate to define a network of fluid flow paths required for the testing procedure. The housing sections are assembled at the surface and then lowered on the end of the drill string (e.g., drill pipes or tubings) to the desired test depth corresponding to a prospective zone of interest.
Inflatable (or otherwise expandable) packers carried by certain of the housing sections engage the wellbore to isolate a test region. A single packer may be provided if only the bottom of the wellbore is to be tested, but it is common practice to provide a pair of packers which permit a test region intermediate of the top and bottom of the wellbore to be isolated.
For conventional testing, weight may be set down on the drill string to expand the packers against the wellbore. For inflate testing, a pump may be positioned in the drill-stem test string to pump wellbore drill fluid (commonly referred to as xe2x80x9cmudxe2x80x9d) into the packers for inflation. Once the packers are set, a test valve is opened to introduce a flow of fluid from the test region into one of the channels formed in the drill stem test string. Upon completion of the initial flow period, the test valve is then closed (i.e., shut-in) to allow the formation to recover and build back to its original shut-in pressure. Repetitive flows and shut-ins are routinely performed to gather additional reservoir evaluation data. The drill stem test system is then retrieved to permit interpretation of the recorded pressure and temperature data and analysis of the fluids and/or gas samples trapped by the DST tool during the flow period.
Typically, the DST tool is conveyed downhole using tubing or drill-pipe to a prospective zone of interest based upon previously measured depth and formation correlation from open hole wireline logs, e.g., a gamma-ray well log. However, during the process of conveying the DST tool with tubing or drill-pipe, improper or inaccurate measurements of the length of the drill string may take place due to inconsistent lengths of collars and drill-pipes, pipe stretch, pipe tabulation errors, etc., resulting in erroneous placement of the DST tool. Thus, DST tests may be performed in the wrong zone of interest, and incorrect decisions may result as to whether the formations being tested is a hydrocarbon-bearing formation. Furthermore, repeating the drill-stem test may be very costly both in expenses and time.
Therefore, a need exists for an apparatus and method for accurately logging a drillstem test tool into place as the DST tool is conveyed by drill pipe or tubing to the desired location.
Apparatus and method for accurately logging a drill-stem test (DST) tool into place as the DST tool is conveyed by drill pipe or tubing to the desired location are provided.
One aspect of the invention provides an apparatus for logging into place a drill stem test tool, comprising: a drill string comprising drill pipes or tubings; a drill stem test tool disposed on the drill string; an electromagnetic telemetry tool disposed on the drill string; and a gamma ray tool connected to the electromagnetic telemetry tool.
Another aspect of the invention provides a method for logging into place a drill stem test tool disposed on a drill string, comprising: lowering a drill stem test tool, an electromagnetic telemetry tool and a gamma ray tool disposed on a drill string into a wellbore; producing a partial log utilizing the gamma ray tool while the drill stem test tool is moved adjacent a correlative formation marker; compare the partial log to a well log to determine a depth position adjustment; and adjust a position of the drill stem test tool according to the depth position adjustment.
Another aspect of the invention provides an apparatus for testing a well, comprising: a downhole system comprising a drill stem test tool disposed on a drill string and an electromagnetic telemetry tool having a gamma ray tool disposed on the drill string; and a surface system comprising a controller disposed in communication with the downhole system.